Article Search

The Difference Between Strong and Weak Acids

Tuesday, October 20, 2009 &nbsp|&nbsp 3 Comments

by Christopher Vasey

In addition to the degree of acidity as measured by the pH scale, acids can be characterized as either strong or weak. In fact, acids are rarely encountered in a free or isolated state; they are most often combined with an alkaline element. When there is the combination of a strong alkaline element and an acidic element, the acid is of little consequence in the combination. The acid is called weak, as it is easy for the body to neutralize it. When the alkaline element is weak, however, the acid content is of much greater consequence. The acid is stable, mixes poorly with other elements, and it is referred to as a strong acid.

Physiologically, strong acids - precisely because of their stability and resistance to combining - are much more difficult to neutralize and eliminate from the body than weak acids.

Strong acids come primarily from animal proteins. They chiefly consist of uric, sulfuric, and phosphoric acids. Their elimination from the body requires significant neutralization, a task performed by the liver as well as the normal elimination work of the kidneys. Because the kidneys can only eliminate a fixed amount of strong acids on a daily basis, however, any excess is stored in the tissues. Consequently, it is important to monitor the consumption of animal proteins.

Weak acids are primarily of plant origin (carbohydrates and vegetable proteins), except for those coming from yogurt and whey, which are of animal origin. Weak acids include citric, oxalic, pyruvic, and acetylsalicylic acids. Weak acids are also called volatile acids, * because once they have been oxidized they are eliminated by the lungs in the form of vapors and gases, both as breath moisture and as carbon dioxide (C02). Their elimination is relatively easy, and there are no limits on the quantity that can be expelled from the body by the kidneys, unlike nonvolatile strong acids. When the body needs to increase the elimination of volatile acids it does so simply by increasing the rate of respiration. The amount of volatile acids that can be eliminated is limited only by how fast and how deeply a person is able to breathe.

*Volatile acids are primarily regulated by respiratory function, as opposed to fixed acids, which can only be regulated by the kidneys and eliminated from the body in fluid form.